1. Metabolic Pathways  Linked reactions, one reaction leads to another  Enzyme – organic catalyst (speeds chemical reaction)  Ribozymes – made of RNA, not proteins, biological catalyst (RNA/protein synthesis)  Substrates – reactants in reaction, act on enzymes -E -

2.  Activation energy – energy needed to start a reaction  Enzymes lower the amount of activation needed in a reaction  Active site – area on enzyme that the substrate binds to.  Induced fit model- enzyme complex undergoes a slight change in shape

3.  Degradative reactions – substrate broken down  Synthesis reaction – substrates combine, larger product  Enzymes are not used up in the reaction, available to bind to another substrate.  Reactions require specific enzymes  Enzymes are sometimes named for their substrates, usually end in -ase

4. Factors that affect speed of enzyme  Substrate concentration  Temperature and pH – leads to denaturing  Enzyme concentration Cofactors – inorganic ion (copper,zinc or iron) Coenzymes - nonprotein organic molecule  Vitamins

5. Enzyme Inhibition  Inhibitor binds to enzyme  Usually reversible  Feedback inhibition – final product of pathway inhibits a reaction Competitive inhibition – substrate and competitor bind, only substrate produces Noncompetitive inhibition – inhibitor attaches to allosteric site, enzymes changes shape

6. Redox reactions  Permits flow of energy to all living things  Oxidation – loss of electrons  Reduction – gain of electrons  Photosynthesis – H+ ’ s, transferred with e ’ s coenzyme NADP+ - NADPH  Cellular respiration – Coenzyme NAD+ - NADH (accepts 2e ’ s and H+)

7. Cont ’ d redox reaction examples  Electron Transport Chain Series of membrane-bound carriers, pass e ’ s from one carrier to another. Photosynthesis/thylakoid membrane Cellular respiration/cristae – inner membrane of mito.  ATP Production ATP synthase complexes – carrier proteins and enzymes Chemiosmosis – production of ATP due to H+ gradient across a membrane